MAPT and supranuclear palsy, progressive, 1: The H1 MAPT haplotype increases PSP risk and has been associated with higher expression of 4R tau, but it is too common in the general population to explain the unusual 4R tau predominance in the present family [25–27] and has previously been shown not to influence the phenotype of FTDP-17 patients with other MAPT mutations [28].